Spray Gun Transfer Efficiency and Material Usage

Transfer efficiency is the share of what leaves the gun that lands on the panel, and it multiplies material consumption directly -- so the difference between a 35% conventional gun and a 65% HVLP gun is not a refinement, it is nearly half the paint. A job needing 1.2 quarts applied takes 3.43 quarts through the conventional gun and 1.85 through the HVLP one, and the 1.58 quart difference at $90 a quart across 700 jobs a year is $99,692. The overspray is not merely wasted material: it is emitted VOC, it is what loads the booth filters, and it is what contaminates the booth, so a low-efficiency gun carries three costs beyond the paint. That arithmetic is why HVLP became both the economic default and the regulatory requirement, and air quality rules in most areas now require HVLP or an equivalent demonstrated transfer efficiency for refinishing. Technique matters as much as equipment, and this is the caveat to take seriously: rated efficiencies are laboratory or standardized-test values, and gun distance, overlap, travel speed, air pressure, and fluid delivery move the achieved figure well away from them -- a well-set HVLP gun in poor hands can transfer no better than a conventional gun in good ones. The honest way to know a shop's real number is to divide theoretical coverage by measured consumption over a month rather than to enter a rating. It does not compute the theoretical coverage a job needs, which comes from the coating manufacturer's technical data sheet at the specified film build; the coating coverage calculator converts volume solids and a dry-film target into that coverage, and the powder coating coverage calculator is the powder analogue of this comparison, where reclaim rather than transfer efficiency decides the answer. It does not select spray equipment, address the regulatory requirement and its recordkeeping, or address booth airflow and filtration, respiratory protection, or the isocyanate exposure controls refinishing requires. The coating manufacturer's technical data, the applicable air district rule, and OSHA govern.

transfer efficiency = material deposited / material sprayed, so the material that must leave the gun is the applied material divided by that efficiency, and the balance (1 - TE) is overspray. The comparison against alternative equipment is the same relation at a second efficiency, and the annual figure is the per-job difference times the jobs entered.

A material consumption and equipment comparison from a transfer efficiency the user supplies. Rated efficiencies are laboratory or standardized-test values (conventional siphon guns commonly 25 to 35%, HVLP 55 to 70%) and the achieved figure depends heavily on operator technique, part geometry, and gun setup. It does not compute theoretical coverage, select spray equipment, or address the air district rule requiring HVLP or an equivalent demonstrated transfer efficiency and its recordkeeping obligations.

One division and a comparison; no manufacturer coverage table is reproduced.

Estimate. AHJ and licensed professional govern.

Field names used by the API: applied_material_qt, transfer_efficiency, alt_transfer_efficiency, price_per_qt, jobs_per_year, material_sprayed_qt, overspray_qt, alt_material_sprayed_qt, saving_per_job_qt, annual_saving_usd

• The efficiency is entered rated figures are test values, not achieved onesthe equipment manufacturer and the shop's own measurement
• Theoretical coverage is entered it comes from the coating data sheet at the specified film buildthe coating manufacturer's technical data sheet
• Not a compliance determination the HVLP or equivalent-efficiency requirement and its recordkeeping are the rule'sthe applicable air district rule